1. Field of the Invention
The invention is directed to a workpiece ejector and transfer apparatus adapted to automatically eject a processed workpiece from a tool and transfer the processed workpiece to an unload position such that a new workpiece can immediately be loaded into the tool and thereby reduce cycle time. The workpiece ejector and transfer apparatus is compact and inexpensive as compared to the use of a robot, and thereby provides increased efficiency as well as reduced congestion of the manufacturing space.
The workpiece ejector and transfer apparatus is particularly adapted to synchronous manufacturing operations wherein a single operator runs multiple tools that are typically arranged in a carousel type configuration. Conventional synchronous manufacturing operations require the operator to manually unload and transfer the processed workpiece to a storage position before a new workpiece can be loaded into the tool and work can be performed. Accordingly, the efficiency can be improved by automatically unloading the tool thereby eliminating the down time during which the processed workpiece is manually unloaded and transferred. Furthermore, the synchronous manufacturing operation can be coordinated to optimize the efficiency of the operator such that a single operator can load and unload multiple tools. While the preferred embodiment of the present invention relates to a welding application, it should be appreciated that the invention may be adapted to accommodate any number of alternate applications.
2. Description of the Related Art
Inoue et al., U.S. Pat. No. 4,779,336 teaches an apparatus for positioning a body panel assembly wherein a swingable platform is supported for swing motion at one end of the slide base which is moved back and forth by a programmable high precision positioning mechanism, such as a servo or pulse motor. The platform having a jig pallet clamped thereto is rotated such that the part held by the pallet may take an assembly attitude and the slide base is moved to transfer the part to a position for assembly to a body. Inoue et al. however, does not provide an apparatus for automatically extracting the workpiece from a tool after work has been performed, such that the workpiece must be unloaded from the tool before work can be performed on another workpiece.
Clark, U.S. Pat. No. 2,969,750 teaches an apparatus for loading and unloading a plating rack from a conveying system. The apparatus includes a pair of transfer devices associated with a shop conveyor and a plating machine having a hydraulic loader. The hydraulic loader includes a hydraulic cylinder and a pair of telescoping arm assemblies that are each pivotally secured at their lower end to a base and attached at their upper end to a central portion of a frame. The Clark invention is, however, limited to loading and unloading a workpiece that is transported by a trolley along the conveyor, and is not adapted to unload a stationary workpiece from a fixed tool. Additionally, the composition of the Clark invention is excessively complex and therefore likely to be expensive and prone to failure.
Rudolph et al., U.S. Pat. No. 3,648,821 teaches an apparatus for transferring workpieces from a first to second location while simultaneously changing the orientation of the workpiece. The invention includes a first transferring apparatus adapted to load a new workpiece and a second transferring apparatus adapted to unload a processed workpiece. The first and second transferring apparatus are located adjacent an endless conveyor having a plurality of uniformly spaced supporting devices. As with the Clark reference described hereinabove, Rudolph et al. is limited to loading and unloading a workpiece that is transported by a supporting device along a conveyor, and is not adapted to unload a stationary workpiece from a fixed tool.
Alexander, U.S. Pat. No. 5,141,093 teaches an apparatus for conveying body panels to and from a workstation along the conveyor using appropriate releasable clamps to retain the panel engaged against the locator pads of the support frame. The apparatus includes a support frame adapted to be mounted along one edge upon the carrier of a conveyor. A number of locating and retaining devices or clamps are mounted at predetermined locations on the support frame such that the work piece is adequately located and retained. The conveyor is provided with a manipulator assembly adapted to pivot the support frame from a generally horizontal conveying position to and from a lowered position where the support frame is adjacent a panel receiving frame. As the Alexander reference is adapted to precisely load a workpiece into a tool and thereafter unload the workpiece, it is unnecessarily complicated and expensive for purposes of unloading a workpiece that was manually loaded. Many of the features of the Alexander reference, such as the support frame with locators and clamps, are provided to precisely load the workpiece into the tool, and in the context of an operation, that exclusively unloads the workpiece, such features are redundant and/or completely useless.
From the above, it can be appreciated that the workpiece ejector and transfer devices of the prior art are not fully optimized. Therefore, what is needed is a simple and inexpensive device adapted to unload a processed workpiece that is either stationary or conveyed along an assembly line, and thereafter transfer the processed workpiece to an unload position while a new workpiece is processed through the tool.